The present invention relates to a novel transparent optical material which has high refractive index, low dispersion and excellent optical property, and is used for a glasses lens, camera lens, prism, substrate for an information recording medium, pickup lens, optical fiber, optical filter and the like, to a plastic lens using this material, and to a method for producing the same. Further, the present invention also relates to a novel selenium-containing compound useful as a raw material for the above-described transparent optical material.
A transparent optical material and a plastic lens are molded articles required to have high transparency and optical uniformity as is apparent from the uses thereof. As a material conventionally used widely in these uses, there is listed a plastic material obtained by radical polymerization of diethylene glycol bis(allyl carbonate) (hereinafter, abbreviated as DAC).
However, this DAC plastic material has low refractive index (Nd) as low as 1.50, and when used for a plastic lens, there is a problem that the resulting lens has large edge thickness and is deficient in fashionable appearance.
For improving this problem, various investigations have been made for increasing refractive index. For example, there are listed a method in which tetrabromo bisphenol-A is reacted with an isocyanate compound (Japanese Patent Application Laid-Open (JP-A) No. 58-164,615), a method in which xylylenedithiol dimethacryalte is polymerized (JP-A No. 64-31,759), a method in which 1,4-dithiane-2,5-dimercaptomethyl is used (Japanese Patent Application Publication (JP-B) No. 6-5,323), and the like.
Also the present inventors have previously suggested methods in which a polythiol having in the molecule a sulfur atom other than a mercapto group is used (JP-A Nos. 2-270,859 and 7-252,207), and the like.
Any of these methods is a method in which refractive index is improved by introducing a benzene ring, a halogen atom such as bromine, or a sulfur atom into the molecule. However, when refractive index is desired to be further improved, these methods have been often insufficient. That is, these methods have not been recognized as methods fully satisfying eager requirement to further decrease the edge thick of a lens.
Accordingly, an object of the present invention is to provide a transparent optical material and a plastic lens which can have further improved refractive index and further decreased edge thickness of the lens.
Further object of the present invention is to provide a novel compound useful for the novel transparent optical material, and a composition containing this compound.
The present inventors have intensively investigated to satisfy the above-described strong requirement, and as a result, found that refractive index can be further improved by introducing a selenium atom into the molecule of an optical material, completing the present invention.
Namely, the present invention provides a transparent optical material and a plastic lens containing in the molecule at least one selenium atom, and a method for producing a transparent optical material and a plastic lens in which a composition containing at least one reactive monomer or oligomer having at least one selenium atom in its molecule is subjected to casting polymerization.
This technique for introducing a selenium atom into the molecule of an optical material has not been known until now.
The present invention contains the following subjects.
1. A transparent optical material which contains at least one selenium atom.
2. A plastic lens which comprises the transparent optical material according to subject 1.
3. A method for producing the transparent optical material in subject 1 which comprises the step of cast-polymerizing a composition including at least one reactive monomer or oligomer having at least one selenium atom in its molecule.
4. A method for producing the plastic lens in subject 2 in which comprises the step of cast-polymerizing a composition including at least one reactive monomer or oligomer having at least one selenium atom in its molecule.
5. The production method according to subjects 3 or 4, wherein the reactive monomer or oligomer having at least one selenium atom in its molecule is selected from selenium atom-including active hydrogen compounds having at least one functional group of a hydroxyl group, mercapto group, seleno group and amino group, selenium atom-including self-polymerizable compounds having at least one functional group of a (meth)acrylic group, allyl carbonate group, allyl thiocarbonate group, allyl selenocarbonate group, allyl group, vinyl group, isopropenyl group, epoxy group, thioepoxy group and selenoepoxy group, and selenium atom-including isocyanates having at least one functional group of an isocyanate group, isothiocyanate group and isoselenocyanate group.
6. A selenium-containing alicyclic compound represented by formula (1): 
xe2x80x83wherein, Y1 and Z1 each represent xe2x80x94CH2xe2x80x94, xe2x95x90CHxe2x80x94, C atom, Se atom, S atom, SO2, SO or O atom, and the hydrogen atom of methylene or methine may also be substituted by a C1 to C3 lower alkyl group, C1 to C3 lower alkoxy group, C1 to C3 lower alkylthio group, F atom, Cl atom or Br atom; X1 represents a functional group selected from an SH group, NCO group, NCS group, acryloyl group, methacryloyl group, vinyloxy group, vinylthio group, vinylseleno group, vinyl carbonate group, vinyl thiocarbonate group, vinyl selenocarbonate group, allyloxy group, allylthio group, allylseleno group, allyl carbonate group, allyl thiocarbonate group, allyl selenocarbonate group, isopropenyloxy group, isopropenylthio group, isopropenylseleno group, isopropenyl carbonate group, isopropenyl thiocarbonate group, isopropenyl selenocarbonate group, epoxy group and thioepoxy group, or an alkyl residue composed of such functional group and an alkylene group having 10 or less carbon atoms. l, m, n, o and p represent an integer of 1 to 5, 2 to 10, 0 to 5, 0 to 3 and 2 to 6, respectively.
7. The selenium-containing alicyclic compound of subject 6, wherein the alicyclic structure is 4 to 10-membered ring.
8. The selenium-containing alicyclic compound of subject 6, wherein the alicyclic structure is 5 to 9-membered ring and the alkylene group is composed of 0 to 4 carbon atoms.
9. A composition including at least one selenium-containing alicyclic compound of any one of subjects 6 to 8.
10. A selenium-containing polythiol having 3 or more functional groups which is represented by formula (2):
xe2x80x83(Z2)qxe2x80x94(SH)rxe2x80x83xe2x80x83(2)
xe2x80x83wherein, Z2 represents an alkylene group having at least one Se atom, q represents an integer from 1 to 20 and r represents an integer from 3 to 6.
11. The selenium-containing polythiol having 3 or more functional groups according to subject 10, which is represented by formula (3): 
xe2x80x83wherein R1, R2, R3 and R4 each independently represents a hydrogen atom, mercapto group, 
xe2x80x83and Y2 represents a sulfur atom or an Se atom.
12. A composition which contains at least one selenium-containing polythiol having 3 or more functional groups described in claim 10.
13. A selenium-containing aliphatic compound having 2 or more functional groups which is represented by formula (4):
(Z3)xe2x80x94(X2)sxe2x80x83xe2x80x83(4)
xe2x80x83wherein Z3 represents an Se atom or an alkylene group including at least one Se atom; X2 represents a functional group selected from an acryloyl group, methacryloyl group and thioepoxy group, or an alkyl residue having this functional group; and s represents an integer from 2 to 6.
14. The selenium-containing aliphatic compound according to subject 13 which is represented by formula (5):
X1xe2x80x94Sexe2x80x94X2xe2x80x83xe2x80x83(5)
xe2x80x83wherein, X1 and X2 are the same or different, and they are each independently selected from the group consisting of: 
xe2x80x83in which Y3 represents a sulfur atom, oxygen atom or Se atom, and R represents a hydrogen atom or a methyl group.
15. A composition which contains at least one selenium-containing aliphatic compound of subject 13.